Post hole digging attachment for portable electric drills



March 6, 1962 J, HEIN ETAL POST HOLE DIGGING ATTACHMENT FOR PORTABLE ELECTRIC DRILLS Filed Jan. 5, 1960 INVENTORS HEIN SlMoN d- MAR'HN a. HEIN :2 WW u ATTORNEY 3,023,630 POST HOLE DIGGIN ATTACENT FOR PORTABLE ELECTRIC DRILLS Simon J. Hein and Martin B. Hein, both of 937 S. Wichita, Wichita, Kans. Filed Jan. 5, 1960, Ser. No. 560 1 Claim. (Ci. 74423) This invention relates in general to a reduction gear drive powered by a portable electric drill and used for driving such tools as posthole angers and the like, and in particular to an auxiliary attachment for a portable electric drill, said attachment including a pair of speed reducing bevel gears with intersecting axes, means for securing said attachment to the drill and means for securing the posthole auger or other driven element to the gear drive attachment.

Designed primarily for portable use in the field where many installation trucks and farm pickups are provided with A.C. power units, or for use where long extension cords will permit movement around a structure for installing fencing or the like, the primary object of the invention is to provide a portable auxiliary attachment removably mountable on a conventional portable electric drill and dr ven thereby, said auxiliary attachment having speed reducing means, and means for receiving a driven tool such as a posthole auger or the like which must be driven at a reduced speed.

Another object is to provide a supporting arm on the auxiliary attachment which provides for securing the auxiliary attachment in place of the removable handle normally found on most large one-half inch portable drills.

Other objects and advantages as well as the construction and operation of the invention will be better understood by reference to the following description in connection with the accompanying drawing in which:

FIG. 1 is a view looking upwardly at the auxiliary attachment, shown in position on a portable electric drill indicated by dotted lines.

FIG. 2 is a vertical cross sectional view through the body of the auxiliary attachment on the line 2-2 of FIG. 1.

FIG. 3 is an elevational view of the attaching member for the auxiliary attachment taken on the line 3-3 of FIG. 1, fragmentary parts being shown in section and elevation.

FIG. 4 is a partial top plan view of the auxiliary attachment with parts being broken away in section to better illustrate certain other parts.

Referring now to the drawing by numerals of reference, 1 designates a housing with upper and lower removable cover plates 2 and 3, suitably secured to said housing.

Oppositely disposed bosses 4 and 5 are provided in the housing, boss 4 carrying an elongated handle 6 and boss 5 rotatably carrying shaft 7, the exposed end 8 of which being preferably hexagonal in shape to be received in the chuck 9 of any suitable portable electric drill 10.

The internal end of shaft 7 carries a bevelled pinion gear 11 and shaft extension 12 journalled in web 13 depending from upper cover plate 2.

Bevel gear 11 meshes with larger bevelled gear 14 which is the output or drive gear of the reduction gear drive attachment, said drive gear 14 being keyed to reduced bevel gear shaft 15 journalled in upper cover plate 2, the lower end of said shaft 15 having an enlarged extension 16 rotatably positioned in depending hub 17 on lower cover plate 3, any suitable driven device 18 being removably secured to said enlarged extension 16.

Housing 1 is provided with an offset socket 19 in which is suitably secured a supporting arm 20, having bifurcated end 21 in which is received stud 22 with enlarged threaded end 23 adapted to be received in the threaded aperture in the electric drill, in which aperture is normally carried the support handle which is regular equipment on most portable drills. This handle is removed prior to application of the threaded end 23 of stud 22. Special adapters in the general form of supporting arm 20 may be used with various forms of portable drills. Shims 24 may be used in order to properly align the supporting arm 20. A suitable nut 25 is received on the stud 22.

Mounting of the reduction gear drive unit to the portable electric drill is a simple matter. After removal of the support handle found on many portable drills, the end 8 of shaft 7 is positioned in the chuck 9 of the portable drill and stud 22 is mounted in the threaded aperture left free by removal of the support handle, said stud sliding freely in bifurcated end 21 of the supporting arm 20 until properly aligned, shims 24 being used to also aid in proper alignment of the supporting arm without binding or warping. When properly aligned, nut 25 is turned to secure the bifurcated end 21 in nonmovable position.

The desired tool 18 is mounted on extension 16 of shaft 15 in any suitable and efiicient manner. In operation of the invention it is necessary merely to hold elongated handle 6 in one hand and the handle 10 of the portable electric drill in the other hand, steadily guiding the driven tool 18.

It is obvious that changes in form, proportion and details of construction may be resorted to without departing from the spirit of our invention and we reserve all rights to such changes as come within the scope of these specifications and the claims which follow.

What We claim as new and desire to secure by Letters Patent is:

A posthole digging attachment for portable electric drills of the type havi g a detachable handle, said attachment including a housing, interengaging speed reduction members mounted in the housing, one of the speed reduction members being driven by the portable electric drill, the other speed reduction member forming a driving member extending from the housing and being adapted to be attached to and drive a tool or the like, and a support member extending from the housing and adapted to be secured to the drill at the point of attachment of the detachable handle on the drill, said support member comprising a pair of separable but normally interconnected members between the portable drill and the attachment housing, means for locking said last-named members together in rigid relation, one of said last-named members adjacent the portable drill being provided with an elongated slotted portion, a fastening member extending through the slotted portion and receivable by the electric drill at the point of attachment of the detachable handle of said drill, the member having the slotted portion being interchangable whereby the posthole digging attachment may be adapted to fit any one of several sizes of portable drills.

References Cited in the file of this patent UNITED STATES PATENTS 1,401,780 Hensel Dec. 27, 1921 2,319,973 Broderhausen May 25, 1943 2,604,795 Ristour July 29, 1952 2,620,840 Schafer Dec. 9, 1952 2,696,129 Riblet Dec. 7, 1954 2,780,942 Babcock Feb. 12, 1957 2,787,265 Neidt Apr. 2, 1957 FOREIGN PATENTS D19074IB/38a Germany Sept. 13, 1956 

